Method of making sheet material



Aug. 18, 1953 1.. H. HILLS 2,649,372

METHOD OF MAKING SHEET MATERIAL Filed Jan. 6, 1950 INVENTOR. AE/Q/VOE/P #445 Patented Aug. 18, 1953 2,649,372 METHOD OF MAKING SHEET MATERIAL Leander H. Hills, Canandaigua, N. Y., assignor to The Garlock Packing Company, Palmyra, N. Y., a corporation of New York Application January 6, 1950, Serial No. 137,187

6 Claims.

This invention relates to an improved method of making flexible, fibrous, moisture resistant sheet material.

The mentioned type of sheet material may be useful for many purposes, as for example, as insoles or mid-soles in shoes, as damping sheets for sound vibrations, as sheet gasket material for sealing or gasketing purposes in mechanical devices, and for various other purposes wherein a flexible sheet is desired which will not become weakened or distorted in shape or otherwise deteriorate in the presence of moisture.

Fibrous sheet material, to be useful for the mentioned purposes, must be strong enough to offer substantial resistance to tearing and to stretching while at the same time it should be quite flexible. Such sheet material has heretofore been made by first producing a Web formed of suitable fibrous material and, preferably, some suitable binder material. Such a web, hereinafter sometimes conveniently referred to as paper, then has been thoroughly impregnated With a mixture of animal glue, glycerine and water to give it sufficient strength for its intended purpose. Then, to render the paper useful in the presence of moisture, the web has again been processed to render the glue therein substantially insoluble by treating it with formaldehyde, or with certain chromium compounds or with combinations of the two.

The results of these prior practices, however, have been far from satisfactory. Such use of formaldehyde does not adequately insolubilize the glue; such use of chromium compounds substantially impairs the flexibility of the paper while insolubilization of the glue is not as fully accomplished as desired; and when chromium compounds, either alone or in combination with formaldehyde, are used as in the past, the control 'of the process is difficult and the final results are not satisfactory.

The principal object of the present invention is the provision of an improved method of making flexible, fibrous sheet material which is useful in the presence of moisture and which possesses the desired strength and flexibility.

According to the process of the present invention, in its broader aspects, a water soluble acid chromate or dichromate is thoroughly mixed with even more complete insolubilization of the glue.

In producing flexible fibrous sheet material according to a preferred manner of practicing this invention, a quantity of paper pulp is made by mixing suitable fibrous material with water and, preferably, with suitable binder material to produce a more or less plastic, slimy batch of pulp. The fibrous material used may preferably be of cellulosic fibres, although fibres of asbestos or lass or a combination of various kinds of the mentioned fibres may be employed. The paper pulp, if desired, may also include granular or pulverulent material such as particles of cork, wood flour or the like.

An aqueous chromate solution preferably is separately prepared by dissolving a quantity of a water soluble acid chromate such as potassium dichromate in water, this solution preferably being a saturated solution. Then the dichromate solution is thoroughly mixed into the paper pulp batch, the relative quantities of the original batch and of the dichromate solution being mixed at this stage being such as to assure that the dichromate solution will completely permeate the batch. It has been found that where potassium dichromate is the chromium compound used in the mentioned solution the preferred proportions to be admixed in forming the chromated batch are approximately parts by weight of the dry fibres (and other solid material if the latter is used) in the initially formed paper pulp batch to .2 part by weight of the dry potassium dichromate.

The chromated paper pulp batch is passed through conventional paper making machinery by which it is formed into a web of a desired thickness after which the web is subjected to suitable drying means in accordance with conventional paper making procedure.

As a practical matter, the chromated paper Web preferably is elongate and substantially continuous in form, enabling it to be rolled conveniently into a compact roll. The chromated paper may then be further treated, according to the process of this invention, either immediately upon emanating from the paper making machine or at some later time by being drawn from a roll. In such further treatment, the chromated paper is thoroughly impregnated with a mixture preferably of from two to four parts by weight of glycerine to one part of animal glue with sufficient water to give the mixture a relatively thin consistency. In order to impregnate the chromated paper, and assuming that the latter is in the form of an elongate web, the web, either as it emerges from the paper making machinery or as it is drawn from a roll, is passed, 'in a substantially horizontal attitude, through a long shallow bath of the mentioned glue-glycerine mixture.

As the-web enters the bath it is inclinedto shallow bath, and the speed of travel of the web" through the bath are all so determined or r egulated that before the web emergesIrcm-the bath.

it becomes completely subniergedtheriifilherby indicating complete impregnation of the web. Upon emergence of the webirom the bath, any

excess of the glue-glycerine *rriixturemay be =re-- moved by any suitable conventional wiping =or, squeezing means.

Upon the glue in the mentioned glue-glycerine mixture permeating the chromated paper and coming into intimate association with the chromate therein, .3, reaction sets in between the chroinatefand the glue whereby the latter is rapidly rendered substantially insoluble while, "at the same time, the paper remains substantially flexible. The thorough impregnation of the paper withthe glycerine andgglue also very substantially strengthens the paper.

After the excess-oi the glue-gly'cerine mixture has been wiped 'or pressed from the web and "the latter is dried, the web 'may' bie'formed "into :a roll from which it may later be drawn for use "for any *of the mentioned purposes for which it may be suitable.

The "accompanying drawing is a representation of sheet material resulting from the "practice of 'the hereinbefore described process. :It showsth'e sheet "in cross-section in greatly enlarged :form

*from which it may be seen that the'sheet'commixture which cannot be conveniently shown in thedrawing, 'but'its presence therein is indicated generally by the reference character c.

The glue greatly strengthens the paper, and as the glue is substantially insolubilized, the :paper is highly rmoisture resistant. Also, when the-sheet material is madeaccording to the present invention, it .is' substantially flexible.

Although the :method .hereinb'efore :describcd Number "yields sheet material in' which the :glue is sufficiently :insolubilized for many purposes, znevertheless, ifor somezother purposes 5as,:for example, "for use as gasketing material, the impregnated sheet material preferably should be :further treated .by the application of-formaldehyde-there- .to. This morecompletely insolubilizes-the;glue

in the sheetmaterial thus making it .more suitparts of the substituted dichromate compound td be used-,per .100 ,parts byweiaht of the dry paper pulp materiail should preferably ibe in the same proportion to .2 as the molecular weight of the substitute compound is to the molecular weight of potassium dichromate.

imtbmghitiis preferred to prepare the dichroma'te solution separately as hereinbefore described, invention, nevertheless, also comnrehtmds taunting the initial paper batch by mixing the dry dichromate with the dry pulp materialand' then'mixing sufiicient water therewith to-gtie ld a batch of the desired consistency in which the dichromate is substantially dissolved ,and thoroughly permeates the batch maticla'imisz 'l. A process of making sheet material which compriseseconverting into web form ,a Wet batch of paper ,pulp comprising pulp material and dis- ,solved dichromate, and impregnating the web paper pulp-materiarwith water to form an initial batch, separately dissolving a'quantity of water "soluble dichromate material which is approximately 02% *by we'ight as compared to the dry pulp'm-aterial used in *forming said initial batch, ='intermixing "the "latter "solution with "said initial batch convertin-g the resultant 'chromated batch to sheet form, and impregnating the I sheet with animal'glue.

LEANDER H. .l-IIL-LS.

. Name .Date 12.44314 -Ayer .l [Lar. 5,187.2 210,655 133al1 Dec, 10, 18778 37211558 Goessmann F Feb. 124i, 1903 122771576 'McEarlane Dec. 18 1923 11735429 Frost Nov. 512 1929 1,929,432 Isaacs Oct. 10,1933 1,9442886 *Goessmann Jan. 30, 1934 2 ,005,397 'Schur "June*l8, 1935 23062164 Bowlby Jan. 25, 1938 25433;849 Lathro'p et a1. Jan. -6, 1948 EOREIGN .EALIENTS :Number Country Date 12,299 {Great Britain. 1of 189,1 Y 24,563 Great Britain Oct. .20, .1894 M1893 237,292 Great Britain Aug. 26, 1926 392,693 Great,-Britain a May 25, .1933 417,234 zGreatrBritain Sept. 24, .1934 595,683 .Great.Britain Dec..l2, 1947 207,212 Switzerland Jan. 2, .1940

":OIBHER REFERENCES Sweat BPaper Industry and "Paper "World, 'Au 

1. A PROCESS OF MAKING SHEET MATERIAL WHICH COMPRISES CONVERTING INTO WEB FORM A WET BATCH OF PAPER PULP COMPRISING PULP MATERIAL AND DISSOLVED DICHROMATE, AND IMPREGNATING THE WEB WITH ANIMAL GLUE. 